There are more air-conditioning options than ever — from so-called ductless split systems to high-efficiency models. We help you choose what’s best for your family.

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WITH SUMMER FAST APPROACHING, now is the time to start thinking about how best to cool your home. Don’t wait until a repeat of the 2011 heat wave, in which one 103-degree July day was the hottest in 85 years and finding a fan or air conditioner for sale was about as likely as having lunch at Locke-Ober with Bigfoot.

Fans and air conditioning do put more stress on the environment, increasing carbon dioxide in the atmosphere by burning fossil fuels and, in the case of most ACs made before 2010, depleting the ozone layer. But with appliance efficiency on the rise and homes better insulated than ever, the amount of energy consumed in this country for cooling, as well as heating, has actually decreased in the past decade — even while the number of houses nationwide with central or room air conditioners has climbed to almost 90 percent. You can cut your home’s need for mechanical cooling systems, but if you’ve tried all of the most environmentally friendly options and found they’re just not doing the job, here’s what you need to know before taking the next step.

Fans can work well on their own, depending on how much cooling you need, or can be used in conjunction with air conditioning to decrease cost and drive up efficiency. Outside of table and floor fans, this category offers three main options:

• Ceiling fans can be effective when the humidity’s not too high. “The first job of an air conditioner is to draw out humidity,” says Jimmy Schiavone, president and owner of Better Comfort Systems in Malden — and fans just don’t work that way, unless you have an exhaust vent, like you would use in a bathroom, installed beside them. But, says Rachel Cluett, a research analyst with the American Council for an Energy-Efficient Economy, in Washington, D.C., “any fan can create a draft so you have a feeling of air rushing across your skin to cool yourself.”

Energy Star-rated fans are about 50 percent more efficient than conventional models; just choose the right size for your room, ranging from 29-inch blades for 75 square feet to 54-inch blades for 400 square feet. You can find a sizing chart at energystar.gov.

“A ceiling fan is a great option to use in conjunction with air conditioning if you have it,” says Cluett. “It will produce a little air movement, which will make the room feel more comfortable even if the temperature might be a bit higher.” According to the council, most people are comfortable with the thermostat set as high as 78 degrees when a fan is running, and with each degree you raise the thermostat, you save 3 percent to 5 percent on air-conditioning costs.

• Attic fans, which cost up to $850 to install, suck hot air, the so-called thermal barrier, from the attic. “Removing the thermal barrier makes it easier to cool the rest of the home,” says William Flannery, owner of Seaway Services, a plumbing and HVAC contractor in Marshfield and Boston. “Attics can reach 150 degrees in summer, and taking that heat away can help your air conditioner work more efficiently.”

• Whole-house fans, mounted on the ceiling of the uppermost floor, pull air in from open windows and draw it to the attic. Contractors generally charge $450 to $650 to install them, not including any additional vents you might need. Whole-house fans must be used only when the air conditioner is off. “Using them in conjunction with the air conditioning,” says Cluett, “basically pulls the air you’ve just spent a lot of money conditioning up and out of the house.” Also, the US Department of Energy warns that if not enough windows are opened throughout the house, the fans can cause a back draft in your utility systems, pulling combustibles like carbon monoxide into your living space and putting your family in danger.

2. ADDING A CONVENIENT CHILL

Window and portable air conditioners are used in New England more than twice as much as in all other regions of the country, in part because they’re easy to install in the area’s older homes. These units, priced from $100 to $1,000 each, are either mounted in a window or positioned nearby with a venting hose that leads to a window. They’re a good solution if you need to cool only a small space or want to lower the temperature for only a few hours. But if you require one in each of two or more bedrooms plus the living room and kitchen, for example, it may be more cost-effective to invest in central air. “They’re not economical in the end,” says Flannery, “because you need more than one, obviously, to cool the house down, especially if you have 1,500 or 2,000 square feet.” Drawbacks include lowered security (it’s easy for thieves to open a window that’s not locked), noise, the units’ less-than-attractive appearance, and blocked sunlight and view.

As with ceiling fans, it’s important to get the right size unit for your room. You can find a calculator, as well as information on how to recycle old models, at energystar.gov.

Christoph Hitz

3. CONSIDERING A NEWER ALTERNATIVE

Ductless split air conditioners have been widely used overseas for years but have only recently started to become popular in the United States, in part because they’ve grown more cost-effective. “In the 1990s I was charging $6,000 to $10,000 to install a ductless split of any size,” says Schiavone. “Now you can get them installed for like $3,500 or less.” Ductless split systems are called this because, unlike a window unit or the old through-the-wall units still found in motel rooms, the system itself is divided, with a cooling coil inside the house and a condenser outside. The two parts are connected only by pipes and wires, so no large hole is cut in the wall. Ductless split systems can provide multi-zone conditioning, with as many as three “heads,” or coils, placed in different rooms and attached to a single condenser that sits outside your house, just as a traditional central AC condenser would. Ductless mini-splits, on the other hand, have one coil for each condenser and are typically used in, say, an addition.

Suited for many older New England houses with baseboard or radiator heat, most ductless split systems house their indoor coils in a long, relatively slim horizontal unit placed near the top of a wall. Some websites note that the units can leak, but according to Schiavone, properly installed and maintained ones shouldn’t. “If you put a bathtub upside down in the bathroom,” he says, “guess what? It’s going to leak. Or if you don’t put bedding compound under the tub or forget to tighten a nut. All those things are installation things.”

It’s important to change the filters every few months — a dirty filter slows airflow and makes the equipment work harder — and to have your unit checked by a service professional every couple of years.

Though leaking may not be a problem, for some homeowners aesthetics are. Ductless split systems are not particularly appealing visually and in many cases not appropriate for those doing historic restorations. “But you can get them where they recede into the wall,” says Flannery. “They don’t have to have exposed heads on them.” In a recent job at a high-end condo on Beacon Hill, Flannery put the coils inside closets, for example, and ran a small duct off them so that the homeowner could see only flat grilles. But concealing your ductless system will add to your bill. “The units themselves are not more costly,” Flannery points out. “It’s just the labor for doing custom work. It’s much easier just to hang something on the wall.”

Christoph Hitz

4. CHOOSING THE WORKS

Central air is something of a Holy Grail in the Northeast, because many of the ubiquitous older homes in the area lack the ductwork that comes with forced-hot-air heating, and installing this ductwork can be costly and inconvenient. “There’s more hot-water heat in New England,” says Ray Gircys, operations manager at Farina Corp., a mechanical contractor/HVAC company in Charlestown. “You could convert and go to a ducted system, but it’s a big project, and anything that’s driven by labor is expensive.”

One AC option for homes that don’t already have heating ducts is a high-velocity system. These work like conventional central air, with an indoor air handler — like a furnace, but instead of heating your home, it cools it — and a condenser outside. Though they’ve been around since the 1960s, high-velocity systems, like ductless splits, only recently became more popular. “High-velocity systems have little 2- to 3-inch ducts,” Gircys says, noting that the larger size, if it fits in your space, is usually less noisy. “They’re good if you have a house with a lot of historical value and beautiful woodwork you can’t cut. You can snake them through ceilings and into walls that you couldn’t do with a conventional system. Sometimes you need to cut the walls open a bit, but the surgery is small compared to a conventional system.” High-velocity systems can cost as much as $10,000, depending on the size of your house and the complexity of the job. Again, any tricky customizing or extra finish work can add to your bottom line.

If you are building new or already have ductwork, of course, central air is a different story. According to the US Energy Information Administration, almost 90 percent of new homes nationwide are constructed with central air. For older homes, says Cluett, the first step to retrofitting a system is to make sure your contractor checks all the ducts. “He should examine them for sealing and insulation,” she says, “and make sure the supply and return systems are balanced. A lot of times it’s really challenging to seal the main duct to the AC unit, and often you get a fair amount of leakage at that point, so special care needs to be given to that area.” Selecting a contractor with North American Technician Excellence, or NATE, or Energy Star training can help; you can find one at natex.org or acca.org, the website of the Air Conditioning Contractors of America.

Next, your contractor will do a “load calculation” to determine just how much power your system needs. “We used to do it on paper,” says Gircys, “but now it’s a computer program that takes into account the size of the house, exposures, walls, windows, how much shading a house has. But that’s basically on new homes. Older homes, a lot of times it’s a guess. They’re not as well insulated, and windows and doors may not be compliant.”

The old rule of thumb, he says, was to install 12,000 BTUs, or British thermal units — equivalent to a ton of air conditioning — for every 500 square feet. “Most home equipment starts at a ton and a half and goes to 5 tons,” Gircys says. “A really big house will have multiples of that. Usually I’ll sit down with people and say, ‘How are you going to use it?’ Some customers say they’ll only turn it on on the warmest days of the year, maybe running it one month total. Me, pretty much that first hot, humid day, I turn it on, close the windows, and live in that environment until it’s 75 degrees again outside with a nice breeze.”

While today’s furnaces and air handlers are up to 98 percent efficient, most older residences with forced-hot-air heat, Schiavone points out, have only 80 percent-efficient furnaces. “That means if you buy a dollar’s worth of fuel,” he says, “80 cents of it goes into heating the home and 20 cents goes out the chimney.” A more efficient system will cost you more but may qualify for a bigger rebate; check energysavvy.com/rebates/MA/ to see what your community offers. With more efficiency, you also get lower running costs throughout the life of the system. “It depends how much you want to hug a tree versus how much it’s going to cost and how much usage you’re going to get out of it,” Schiavone says.

If your furnace is, say, 10 or 15 years old, you can still retrofit it with an air handler, but, says Gircys, “you will not get the efficiency of a matched system, and it’s not worth buying at the high end unless you’re going to change the furnace, coil, and everything. I’ve seen furnaces 30, 40 years old. At that point I’d say change it. If it’s 10 years old, do the coiling, keep the furnace. It could break down, but chances are you’ll be all right.” Another consideration: Higher-efficiency equipment is much larger and may not fit into the existing space, so you may need to move a wall or two.

To keep your central-air system running well, as with ductless splits, change the filters every two or three months and have a professional do a checkup every two or three years. Installing a programmable thermostat can make a big difference. Consider one that can be adjusted remotely. “What if you’re at work and the AC is programmed to go on one hour before you go home,” says Flannery, “but you get stuck in a meeting?” Then you wouldn’t have to worry about cooling an empty house for hours.

Which brings us to a common misconception that’s costing Americans money: “Your system does not have to work harder when you get home to cool down a house that’s heated up,” says Cluett. “It actually reaches maximum efficiency when it’s running at full speed, which it will do when the house is very warm, instead of running at low speeds for short intervals throughout the day.” In other words, if you’ll be gone for more than an hour, turn the AC off. It doesn’t take that long — and costs less — to cool the place once you return.

Installation starts at $4,000 and can run three or four times that — though arguably worth it for a job done right. “If you go buy, let’s say, a Hyundai,” says Gircys, “you can go to every dealer and when you leave they’re all basically the same. But when we do air conditioning, you are buying a custom product. People want to get the lowest price, and I understand that’s everybody’s nature, but I have a lot of people who buy a headache. I’ve literally had people who call me and they cry. You can take the best equipment on earth, and unless you put it in right, it’s going to be a nightmare.”

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CHILL OUT: YOUR FIRST STEPS

• Turn off heat-generating appliances like lamps and computers when they’re not in use; line-dry clothing, and run the dishwasher in the evening, when it’s cooler outside.

• Paint your home a light, sun-reflecting color, and if you need to replace the roof, go with metal roofing or lighter-colored shingles.

• A lot of heat comes in through the windows. Keep the sun outside with awnings, reflective film or coatings, covered porches, shutters or shades, or trees, shrubs, and climbing vines.

• Updating windows, caulking molding on exterior walls, and insulating make a big difference in energy efficiency in summer and winter.

• Install a turbine vent in the attic. It works with the breeze, rather than electronically, to help pull warm air out of the house.

Elizabeth Gehrman is a frequent contributor to the Globe Magazine. Send comments to magazine@globe.com.